Air supply system



Feb. 1, 1966 B. SCHRAMM ETAL 3,232,340

AIR SUPPLY SYSTEM 2 Sheets-Sheet 1 Filed March 26, 1963 ENGINE COMPRESSOR FIG.

INVENTORS LESLIE B. SCHRAMM &

ROBERT D. HARLOW BY Q gum w, id yfl iy ATTORNEYS Feb. 1, 1966 B SCHRAMM ETAL 3,232,340

AIR SUPPLY SYSTEM Filed March 26, 1963 2 Sheets-Sheet 2 COMP R ESSOR RECEIVER COMPRESSOR RECEIVER INVENTORS LESLIE B. SCI-IRAMN 8:

ROBERT D. HARLOW ATTORNEYS United States Patent 3,232,340 AIR SUPPLY SYSTEM Leslie 1}. Schramm, West Chester, and Robert D. Harlow, Eaton, Pa., assignors to Schramm, Inc., West Chester, Pa., a corporation of Pennsylvania Filed Mar. 26, 1963, Ser. No. 268,098 4 Claims. (Cl. 165-103) This invention relates to an air supply system of the type providing a supply of compressed air or similar gas and has particular application to compressed air supply units for use by contractors as the supply for various tools operated by compressed air, such as drills, sandblasters, pneumatic tools and the like.

The users of compressed air units of this type employ the unit in many diiierent applications. In some of these applications of the unit cool air is desirable. In other applications of the unit it is preferable to have a supply of hot air to get. maximum energy and more volume. For example, a higher temperature air supply is advantageous for pile driving, sandblasting and other high power consuming operations. In the case of sandblasting, the higher temperature air supply has an additional advantage in that condensation on the sand is reduced.

It is the general object of this invention to provide a compressed air supply system of the indicated type which is versatile in that it may be adjusted easily to supply air at various temperatures.

The above and other objects and features of the invention will become apparent from the following description when read in conjunction with the accompanying drawings in which:

FIGURE 1 is a diagrammatic view illustrating a compressed air supply system in accordance with this invention incorporated in another type of unit; and

FIGURE 2 is a diagrammatic view illustrating a compressed air supply system in accordance with this invention as incorporated in another type of unit; and

FIGURE 3 is a diagrammatic view of a unit similar to that shown in FIGURE 2 with the exception that no aftercooler is provided.

In the diagrammatic views in the drawings the parts have been arranged in the same relative positions as actual embodiments although the various components are illustrated diagrammatically.

As will be apparent hereafter, the principles of the invention are applicable to both stationary and portable air supply units which may or may not have an aftercooler.

The air supply system shown in FIGURE 1 is constructed to be portable and includes a frame portion which comprises a pair of spaced horizontally extending conduit members 16, 12 and 14 and a horizontally extending frame member 16. The frame portion may be mounted on a wheel supporting structure or other means for providing portability. The members 14 and 16 extend between the members and 12 at opposite ends thereof and are secured thereto to provide a rigid construction. The conduit members It 12 and 14 are interconnected to provide a flow passage therethrough and serve as an elongated receiver for the unit as will be described hereafter. p

A compressor 20 and an internal combustion engine 22, which are illustrated diagrammatically, are mounted on the frame for the unit. The engine 22 is arranged to drive the compressor 20 through a suitable drive connection 24. The compressor and engine combination may be of any suitable type Well known in the art and may take various forms. For example, the compressor may be either a piston positive displacement type or a rotating type. Moreover, the engine may be of other types than an internal combustion engine.

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The compressor 20 delivers compressed air through a line 24 to an aftercooler 26. The aftercooler may be of any suitable well known construction in which air or water serves as the cooling medium. Cooled air passes from the aftercooler 26 through an inlet line 28 into the inlet end of the elongated receiver which comprises the conduit members It), 12 and 14. The air is discharged from one end of conduit member 12 through a discharge or service line 30 to the point of use. A throttle valve 32 is connected in line 30 to regulate the flow therethrough. The inlet line 28 and conduit 14 are connected to opposite ends of conduit 10. Also, the discharge line 30 and conduit 14 are connected to opposite ends of conduit 12. By reason of this construction there is provided a receiver of an elongated construction, which construction has significance as will appear hereafter. The air passes through the receiver in the direction indicated by the arrows in the drawing, i.e. sequentially through conduit member 10, conduit member 14 and conduit member 12.

In accordance with the embodiment shown in FIGURE 1 means are provided for bypassing the aftercooler 26. Such means comprises a line 34 which is connected between conduit 24 and the conduit member 12. Line 34 is connected to conduit member 12 at a location near the discharge outlet thereof. A throttle valve 36 is connected in line 34 to regulate flow therethrough. The throttle valve 36 may comprise a plug valve which provides a throttling action by positioning of the valve member at various settings. Preferably, a dial and pointer is provided to indicate the various settings of the valve 36.

Illustrative temperature conditions for a typical air supply unit in accordance with this invention may involve a temperature of the order of 420 F. at the outlet of the compressor and a receiver temperature of F. to 200 F. Without the use of an aftercooler, the receiver temperature of a comparable unit is from 250 F. to 300 F.

During the use of the apparatus in accordance with this invention, the throttle valve 36 is set to proportion the amount of bypass flow through conduit 34 so that the mixture of this bypass flow with the how through the attercooler will provide air having a desired temperature at the outlet line 3%. The throttle valve 36 may be set to a fully opened condition, a fully closed condition and various intermediate positions. Accordingly, by varying the setting of the valve 36, the temperature of the outlet air may be varied.

If a user of the apparatus desires to have cool air, the throttle valve 36 may be set to the closed condition so that all of the air from the compressor passes through line 24, the aftercooler 26 and the receiver to the outlet line 30. However if the user desires hot air, the valve 36 is set to a desired open position to provide a mixture of the hot air from the compressor with the air which passes through the aftercooler.

The construction and arrangement in accordance with this invention wherein an elongated receiver has the air inlet at one end and the air discharge at the other end and wherein the connection of the bypass conduit 34 to the receiver is at the discharge end thereof results in several advantages. Firstly, when the valve 36 is set to bypass hot air to the receiver, there will be a greater percentage of hot air passing through the discharge line as compared with an arrangement wherein the connection of the conduit 34 to the receiver is at some upstream lo cation. This is the case since there is a greater resistance to flow through the long receiver than through the bypass line and since the entrance of hot air at the discharge end of the receiver provides a blocking action against the flow of cool air through the long receiver. Accordingly, higher air supply temperatures and more rapid response to throttle valve action may be achieved.

Another advantage of the elongated receiver construction is that it serves to cool the air as it passes through the elongated path defined thereby. This cooling action results from the heat transfer relationship between the receiver and the cooler ambient air. Accordingly, when the throttle valve is set for cool air, cooler air is delivered at the discharge end of the receiver as compared with a shorter receiver construction.

The form of the invention shown in FIGURE 2 is substantially the same as that shown in FIGURE 1, the only essential difference being that the FIGURE 2 form is a unit which may be either stationary or portable wherein the receiver takes the form of a large tank which is mounted on a frame along with the compressor and the engine. In view of the similarity between the forms of the invention shown in FIGURES 1 and 2, corresponding parts have been given like reference numerals with primes added.

The unit shown in FIGURE 2 comprises a receiver consisting of a large tank, a compressor and an engine 22' arranged to drive the compressor through a driving connection 24. The compressor delivers compressed air through a line 24' to an aftercooler 26'. Cooled air passes from the aftercooler 26 through an inlet line 28' into the inlet at the one end of the receiver 10. Air is discharged from the receiver by way of outlet line 29 at the other end thereof. Line 29 communicates with the discharge or service line 30' which is connected to the point of use. A throttle valve 32 is connected in line 3%) to regulate flow therethrough.

The means for bypassing the aftercooler comprises a line 34' which is connected between line 24 and line 30. It will be noted that the line 34' is connected to the discharge end of the receiver 10. A throttle valve 36' is connected in the line 34 to regulate flow thercthrough. e

The throttle valves 32 and 34 are of the same type employed in the FIGURE 1 form of the invention.

It will be apparent that the operation of the unit of FIGURE 2 will be the same as the unit of FIGURE 1. During the use of the apparatus, the throttle valve 36' is set to proportion the amount of bypass flow through the conduit 34' so that the mixture of this bypass flow with the flow through the aftercooler and the receiver will provide a mixture of air having a desired temperature at the outlet line 39. It will be apparent that this form of the invention will have the same advantages as the portable form described above.

The form of the invention shown in FIGURE 3 is substantially identical with that shown in FIGURE 2 whereby corresponding parts have been given the same reference numerals. The only difference between these forms of the invention is that the aftercooler has been omitted from the unit shown in FIGURE 3. While the range of temperature regulation may be less with the FIGURE 3 form of the invention because of the omission of the aftercooler, a substantial temperature regulation may be achieved because'the temperature of the air at the outlet of the compressor is higher than the temperature at the discharge of the receiver because of heat losses. Accordingly, in this form of the invention the throttle valve 36 regulates the temperature of the air between the high temperature at the outlet of the compressor and the lower temperature at the outlet of the receiver. Of course, the operation of the unit without the aftercooler is the same in all other respects.

It is thus apparent that the compressed air supply system in accordance with this invention may be used to provide compressed air at various temperatures. Accordingly a versatile apparatus having many applications is provided.

Suitable control means (not shown) of conventional type, providing, usually, unloading of the compressor, and slowing down of the engine, may be provided to control operation of the engine-compressor unit to maintain the desired supply pressure at the receiver outlet.

It is apparent that various changes may be made in the construction and arrangement of parts without departing from the scope of the invention wherefore it is not desired to be limited except as required by the following claims.

What is claimed is:

1. A system for supplying compressed gas at a high pressure to pneumatically operated tools or the like comprising a compressor for producing a discharge of compressed gas, an elongated receiver tank for storing a substantial volume of compressed gas, means interconnecting said compressor and said receiver tank for the flow of compressed gas from said compressor to said receiver tank, said first interconnecting means including an aftercooler for cooling the compressed gas passing and being connected to said receiver tank near one end thereof, means for discharging the gas from said receiver tank near the-opposite end thereof, and second means interconnecting said compressor and said receiver tank, said second interconnecting means having a throttle valve connected therein for regulating the flow therethrough, the upstream end of said secondinterconnecting means being connected to said first'interconnecting means at a location upstream of said aftercooler, said secondinterconnecting means being connected to said receiver tank at a location near the discharge end thereof.

2. A system for supplying compressed gas at a high pressure to pneumatically operated tools or the like comprising a compressor for producing a discharge of compressed gas, an elongated receiver tank in heat exchange relationship with the ambient atmosphere for storing a substantial volume of compressed gas, said tank having an inlet near one end and an outlet near the other end thereof, first conduit means in heat exchange relationship with the ambient atmosphere directly interconnecting the discharge of said compressor and said inlet of said elongated tank for the flow of compressed gas from said compressor to said tank, second conduit means directly interconnecting the discharge of said compressor and said outlet of said elongated tank for the flow of gas bypassing said tank, the gas passing through said first conduit means to said inlet and through said elongated tank to said outlet being cooled a greater amount than the gas passing through second conduit to said outlet, means for delivering gasfrom said outlet to the tools to be operated by the supply system, and valve means for varying the mixture of the gas passing to said outlet through said first conduit relative to the gas passing to said outlet through said second conduit to thereby regulate the temperature of the gas supplied to the tool through said delivering means.

3. A system according to claim 2 wherein said first conduit means includes an aft'ercooler for cooling the compressed gas passing to said inlet.

4. A system for supplying compressed gas at a high pressure to pneumatically operated tools or the like comprising a compressor for producing a discharge of compressed gas, an elongated receiver tank in heat exchange relationship with the ambient atmosphere for storing a substantial volume of compressed gas, first conduit means in heat exchange relationship with the ambient atmosphere interconnecting said compressor and said receiver tank for the flow of compressed gas from said compressor to said receiver tank, said first interconnecting means being connected to said receiver tank near one end thereof, means for discharging the gas from said receiver tank near the opposite end thereof, second conduit means interconnecting said compressor and said receiver tank, said second conduit means being connected to said receiver tank at a location near the discharge end thereof, the gas passing through said first conduit means to said one end of said tank and through said tank to the discharge end thereof being cooled a greater amount than the gas passing through said second conduit means to the discharge end. Qf said tank, and valve means for vary- 5 6 ing the mixture of the gas passing to the discharge end References Cited by the Examiner of the tank through said first conduit means relative to UNITED STATES PATENTS the gas passing to the discharge end of said tank through 2,391,838 12/1945 Klelnhans et a1. 165-103 X said second conduit means to thereby regulate the tem- 3,053,247 9/1962 Bradshaw perature of the gas discharged through said discharge 5 means. JAMES W. WESTHAVER, Primary Examiner. 

1. A SYSTEM FOR SUPPLYING COMPRESSED GAS AT A HIGH PRESSURE TO PNEUMATICALLY OPERATED TOOLS OR THE LIKE COMPRISING A COMPRESSOR FOR PRODUCING A DISCHARGE OF COMPRESSED GAS, AN ELONGATED RECEIVER TANK FOR STORING A SUBSTANTIAL VOLUME OF COMPRESSED GAS, MEANS INTERCONNECTING SAID COMPRESSOR AND SAID RECEIVER TANK FOR THE FLOW FOR COMPRESSED GAS FROM SAID COMPRESSOR TO SAID RECEIVER TANK, SAID FIRST INTERCONNECTING MEANS INCLUDING AN AFTERCOOLER FOR COOLING THE COMPRESSED GAS PASSING AND BEING CONNECTED TO SAID RECEIVER TANK NEAR ONE END THEREOF, MEANS FOR DISCHARGING THE GAS FROM SAID RECEIVER 